Electric headlight dimming and compensating means



J. R. MCFARLIN ET AL ELECTRIC HEADLIGHT Dmuuc AND cournsn'xna xmms FiledJnn. 14, 1920 2- Sheets-Sheet l I6 4 L l 15 3f? 7 I.

3f fr f S 10 l 11 F,lg7.i 2'

Oct. 20, 1925. 1,557,716

J. R. MCFARLIN Er AL ELECTRIC HEADLIGHT DIIMING AND COMPENSATING IENS 2Sheets-Sheet 2 Filed Jan. 14, 1920 7a Patented Oct. 20, 1925.

UNITED STATES PATENT OFFICE.

JOHN R. MUFARLIN, 0F PHILADELPHIA, PENNSYLVANIA, AND ELVY G. MCALLISTER,

0F AUDUBON, NEW JERSEY, ASSIGNORS T0 ELECTRIC SERVICE SUPPLIES COM-PANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRIC HEADLIGHT DIMMING AND COMPENSATING MEANS.

Application led January 14, 1920.

To all whom it may conce-m.'

Be it known that we, JoHN R. MclVARLiN and ELvY G. MCALLISTER, citizensof the United States, and residents, respectively, of Philadelphia,county of Philadelphia, and State of Pennsylvania, and of Audubon,county of Camden, and State ot' New Jersey, have jointly inventedcertain Improvements .in Electric Headlight Dimming and (lompensatingmeans, of which the following is a specification.

This invention relates to improvements in the means for dimming electricheadlights` `disclosed in Letters Patent of the llnited States No.1,322,917, dated November 25th. 1919, and has as its primary object theprovision of a set of car and headlight lamps, with means for dimmingthe headlight lamps without varying the brilliancy of the car lamps andfor automatically inserting a compensating or equivalent resistance incircuit with the car lamps to replace a headlight lamp that is detached,burnt out or broken, the system being of such character that the carlamps will burn at constant brilliancy whether the headlight lamp be atfull brilliancy, dimmed or out.

The invention comprises a circuit in shunt relation to the headlightlamp in combination with a relay in circuit with the lamp, the relaybeing excited by current through the lamp to open the shunt circuit andthe shunt circuit being automatically closed when the relay isdeenergized by breaking the circuit through the lamp.

The shunt circuit is provided with a compensating resistance which maybe equivalent to that of the headlight lamp either alone or with theaddition of series resistance so that the car lamps shall burn always ata substantially constant brilliancy, and provision is made for variouslydimming the headlight lamp.

In the drawings, Fig. 1 shows diagrammatically a lay out providing forburning serially arranged car lamps at fixed t'ull brilliancy when theheadlightburns at full brilliancy, dimmed brilliancy or is out; Fig. Qshows a second lay out by which the car lamps are burned at fixedbrilliancy while the headlight may be at higher dimmed brilliancy andutilizes only a portion ot the shunt resistance to compensate for theinoperative headlight lamp; Fig. 3 illustrates a Serial No. 351,462.

lay out in which a separate compensating resistance unit is alonesubstituted For the inoperative headlight lamp in the full brilliancyposition ot' the switch while series and shunt resistances with relationto the headlight are substituted when the latter becomes inoperative inthe dimming position of the switch, and Fig. '-1 is a lay out in which adouble pole double throw snap switch is substituted for the single poledouble throw switch ot the previous lay outs with provision Ytor a widerange of dimmed brilliancy oi the headlight lamp and compensating for aninoperative headlight by resistance in series and part of resistance inshunt relation therewith.

ln the. application of the invention as' illustrated in thc drawings,the trolley wire 1 supplies current to the movable contacting conductor2 containing the lamps 3 tor illuminating the interior of the car.

As illustrated in Fig. 1, the conductor i2, which extends Jfrom theconductor l to ground, contains, in addition to the lamps the seriesresistance 4, the relay coil 5 and the headlight lamp 6.

A conductor 7 connects the conductor' 2, between the lamps 3 and theresistance el, with a terminal 8 which is adapted to be connectedautomatically, by the armature 9 when the relay is deenergized, with theterminal 10 of a conductor 11 which contains the resistance 12 and isconnected with the conductor 2 between the lamp 6 and thel ground,providingl a shunt circuit around the headlight lamp with a shuntresistance equal to that o1 the lamp.

A single pole double throw switch 13 has a blade 11 adapted to connectthe points 15 and 18 in the conductors 2 and 11 and alternatelytherewith the points 16 and 17 in the respective conductors 2 and 7.

When the blade let is set to connect the points 16 and 17, current flowsbetween the source ot current 1 and the ground by way of the conductors2, 7 and 14, through the serially arranged lamps 3, coil 5 and lamp 6,the resistance 1 being short circuited and the relay 5 being excited tobreak the shunt circuit around the lamp G which now burns at fullbrillian'cy.

When the lever 14 is set to connect the points 15 and 1S, current flowsbetween the source of supply 1 and the ground through Q 1,557,711 y ,l.

the conductor 2, containing-the seriali arrangedlamps 3,'ritdnce 4, coil5 and amp 6, and from the conductor 2 through the shunt circuitcomprising the blade 14 and the 'ctiiiiiictr 11 with the 'resistance 12therein to' thecol'idctr 2,bween"the lamp 6 a`d'th'e`g'o'iid,vvtfit'h'the result that the headlight lamp is dimmed without changingthe brilliancy of the lamps 3 since the resistances are proportioned sothat the Pesistance between the source of supply 1 and thegroundhashotbe'en changed substantin fyin either sitoh of the blade 14, withthe headlight am f6 dimmed or burning at full'irilliancy, thls'iamp'should be b'roken, the 'coil 5 "s'deuergized by'the interruptdn orf itscircuit andthe armature 9 drops se stossnnett uis peints s' arid-1o,whereupoucutent owsrokn the source of supply 1 to the gmund=ifh"rm1-ghthe conductors 2,- a, 7,9, 11 ttnd12. AAs the-shunt resistance 112ieFqualuothat f @heluhp the lamps '3 centime-whim at Ifull utiliiaiicy.

In Fig. 2, the dchductor 2 cntains the serially arranged efr lamps 3,resistance 4, relay coil 5, and headlight lanp"6,pas'sing tlitmightlisswiteh peints 15 and 1e. The conductor i7ctiruefsthe 'conductor 2betWnhe'lampSB-'nd ther'stice 4 with the switch point 17 fandfhe contact8 which is adaptedto be ctiectdwit'h the contact 10 'by the armature?.The clitact 10 is cdnnected by la cohuueor 11 a conductrll 'whichconnects the switch point IB'lhro'ugh the 'restance'12 with theconductor 2 between the lantpf Band theground, the ceiiduetsr 11* lis )aterminal 11' ssnnected timdiately of the 'resistance 12.

'Wllsn tliebiaue 14 '5f the fs'with'ie eenn'sst'sthe ptirits 1e indu-'1,siirtentfiidwsfbstWeWtheurce' fl'rc 1 'hdhe gmtiiid throughths'feoudutcrs 2,-3,7,-14, 5 and 6. AThe'llflailig'lit lafnrp takes thefull current and burns 'ntiftll brillan-icy; the rssitance 4 'beingshort ciicuiled fand "the shunt tirtuit (thmu'ghfths cometer-s 7, 9,11*l and 11b containing a sectiohfiof'the resithceQ "being 'broken by?the uc'tin of the excited coil 5 which iaengages the armature 79fromthe' cdntacts Sa'nd 1'0.

f1f,"new,tfhs lmp e should 'become inoperative, the coil 5 lvtiudhe`eenerg'lzecl and the atf'ttl're 9 would (lmp to connect the pHtsS alud10,"whrupon current would How' btweehthesource of supply 1 and the,Qn'dund through A(alle conductors 2, 8, 7, 9,

1r, i1b and a secties eflths resistance '12" adapted to maintain ltheflafiu'ps'?, at 'constamt brilliaiiy.

When the switch "lev'ri14 iset to connect the points 15 and 18,k(livided current flolv'vs fin'fthe ptnt 15 to ground, on t'he one hund'through the conductor 2, coil 5 and lamp' 6 and on the other throughthe blade '14, cqnducter 11 and mism ce 12' is deenergizti` randthevarnturei-,Q 'the points 8 and L10, wher n eureent ows l through theshunt circuit" rom the point 17 through thecondnctortamture 9, con`ductor 11, conductor 11 and a section of \.`1`^-" the resistace 12',`the brilliancy of the Tl lamps 3 being maintained by the compensatingsection ofresistance in the shunt cir-'f cuit equal to that'of the lamp.

As illustrated in Fig.- 8, the source of current 1 is connected withtheIteilindA through M' the conductor 2'cohtainin 4liz "33h91 'lresistance 4, the relay coi' 'ahd't e heidlight lamp 6.Aesmectdrfwsnnects'me; conductor 2 between theiiips' hd'tiiie,resistance '4 *with the M115 df 'the l" 13. A conducto? 7 Withftlitlconductor 2 between the resiwei i the @0115,csnnetts theswtehipointfsf'iwit the terminal 8 adagted to'efnt the relay armtu're i.withwei ance 12",lihe'condl1ctor 11* bilgcheda with the point 16'OftheS19*li$Ch lf3' Ua with the conductor I2 betwe'en thelliup theground. A contlictor" containn'gtl resistance 4 connectstheeonductet- 2between the resistance 4 'and Cthe "conductor with the switch point 17.l When the switch lever` 14 connects the points 15' and 18', currentliews betwee'itlie t @neuster 1 site titsI gmini through the conductors2, 3,7514', 7, 2,"5 andiftlie y. resistance 4 being short circuited, thecircuits 'containing the 'resistsiicesi' dhd12" bein broken, andthe'lnlip'bruinglf ,W full rillinc If, now,"t e lampfshohld burn out'otMfQ break, the coil '5 is deenegizd arr'd the armature 9 'drops toconnect the Apoixts 8' and 10', upon which cmrhtflows btweel theconductor land'the'gtmdthough the '-zf, conductors 2, '3, 7", 14',7","9,'11. Y2" dhd 2, 1 providing the compensatng'resistance uecsIessai-y for mainttining the lamps 3 "at the same brilliancy. n,

Whenthe switch lever 14' connects"the` W points 16'l dnd-17', the sdurceof 'ouirehtr and'the g'rot'fnd are connected 'through the circuitcomprising conductors v2,3, 4,5 and 6, and'throu'gh' the llmtcircdcbmpri's'in the conductors 234', 141- and mami ghe lamp 6,Whichburhs vtiih""dfi'tl'l'med'briliancy. s If, *ndwfthe' la'up' 6'bunsiitfso'thtl the coil 5 is deenstgized arkilthe 'amm 9 connectsthe'pntsS and-'10',cui'eiltws between the conductor 15nd the 1' in g.shunt relaton'to'the lallipth'oug vthe ircuit comprising the conduttore2, 3, 4,11*', 9, 11, 12", and 2, und through 4', 2514' I ill and 11,providing the resistance necessary for maintaining the lamps 3 at thedesired brilliancy.

- As illustrated in Fig. 4, the trolley wire 1 is connected by theconductor 2 containing the 1am s 3 and the resistance 4" with the point1? of the double pole double throw switch 13a; the conductor 2"containing the resistance 4 connects the conductor 2' between theresistance 4" and the point; 17 with the switch point 15; a conductor 7connects the conductor 2', between the lamps 3 and the resistance 4",with the switch point 17"; a conductor 2" containing the relay coil 5and the headlight lamp 6 connects the switch points 16a and 16b with theground; a conductor 11d connects the switch point 18 with the conductor2" between the lamp 6 and the ground and with the contact point 8",which is adapted to be connected by the relay armature 9 with theterminal 10" of a conductor 11e which has a connection 11" with theresistance 4"' intermediately thereof.

When the switch blade 14 connects thc points 16*l and 17h, thecoordinate-blade 14b being on the disconnected points 15b and 18",current flows between the trolley wire 1 and the ground, through theconductors 2', 3, 7C, 14a, 2", 5 and 6, the circuits through theresistances being broken and the lamp 6 receiving the full currentcausing it to burn at full brilliancy.

lf, with the switch blade 14a connecting the points 16 and 17", the lamp6 be broken, the armature 9 connects the pointsS" and 10" and currentflows around the lamp 6 from the conductor 1 to ,ground through theconductors 2', 3, 4, 4' 11e, 9 11", including a section of theresistance 4"' making with resistance 4" an equivalent resistance forthat of the lamp 6.

lVhen the switch blade 14a connects the points 16b and 17a and the blade14b connects the points 15Il and 18, current flows between the conductor1 and the ground through the circuit comprising the conductors 2', 3,4", 14, 2", 5 and 6 and through the shunt circuit 2", 4"', 14" and 11,dimming the lamp 6.

If, now, the lam 6 burns out, the armature 9 connects t e points 8" and10", whereupon the current from the conductor 1 flows to ground throughthe conductors 2', 3, 4, 4"', 11e, 9 and 11d, the section of thesubstituted resistance from 4"' plus the resistance 4" being equivalentto that of the lamp 6.

Having described our invention, we claim:

1. In a lighting system, a circuit comprising a set of lamps arranged inseries; an auxiliary circuit around a lamp aforesaid and provided withresistance approxiniately equivalent to that through said lamp; saidcircuits having means for automatically opening and closing saidauxiliary circuit when the circuit through said lamp is closed and openrespectively, and means for passing divided current through said lampand resistance so as to reduce the current through said lamp relativelyto that through the remainder ot' said lamps.

2. In a lighting system, a circuit comprising a set of lamps arranged inseries; an auxiliary circuit around a lamp aforeasid and provided withadjustable compensating resistance; said circuits having means forautomatically opening and closing said auxiliary circuit when thecircuit through said lamp is closed and open respectively to substitutesaid resistance for that of said lamp when the latter is inoperative,and means comprising a manually operated switch tor passing dividedcurrent through said lamp and resistance so as to reduce the currentthrough said lamp without substantially varying the current through theremainder of said lamps.

3. In a lighting system, the combination with lamps connected in series,dimming resistance, and switching mechanism operable to interpose oreliminate dimming resistance between lamps aforesaid, of compensatoryresistance connected in series with said dimming resistance and in shuntwith one of said lamps in the dimming position of said switchingImechanism, and a circuit controlled by the lamp last named forconnecting said compensatory resistance in series with the remainder otsaid lamps in either position oi said switching mechanism.

In testimony whereof we have hereunto set our hands, this 12th day ofJanuary,

JOHN R. MCFARLIN. ELVY G. MCALLISTER.

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